tert-Butanol → (3-o-Tolyl-isoxazol-4-yl)-carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of 3-o-tolyl-isoxazole-4-carboxylic acid (930 mg, 4.58 mmol, 1.0 equiv), diphenylphosphonic azide (1.26 g, 4.58 mmol, 1.0 equiv) and triethylamine (463 mg, 4.58 mmol, 1.0 equiv) in tert-butanol (40 mL) was heated to 85° C. for 16 hours. The mixture was concentrated under vacuum and the residue taken up into ethyl acetate and sequentially washed with 1M HCl aqueous solution, saturated aqueous sodium bicarbonate solution, water, and saturated aqueous sodium chloride solution. The collected organic was dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum. The residue was purified by flash column chromatography on silica gel (gradient: 0 to 15% ethyl acetate in cyclohexane) to afford 943 mg (75%) of (3-o-tolyl-isoxazol-4-yl)-carbamic acid tert-butyl ester. LCMS (ESI) m+H=275.0; 1H NMR (300 MHz, CDCl3) δ: 8.92 (s, 1H), 7.47-7.29 (m, 4H), 5.87 (s, 1H), 2.29 (s, 3H), 1.48 (s, 9H).

Provenance & Evidence